I have to agree with the op. I understand skipping the low level trash mobs in the public areas. I do that all the time. But skipping the mobs in the instanced area is stupid. It doesn't add but maybe 5 minutes total to the run. It nets me at least 2-3 blue engrams per run. Which in turn levels the cryptarch much faster. I've received more legendaries from the cryptarch packages than I have from the end of mission rewards. With marks capped weekly you may as well spend that extra 4-5 minutes per run.